1. Field of the Invention
The present invention relates to a shock absorbing device for use in a midsole of a footwear such as shoes, sport shoes, military shoes, mountain-climbing shoes, etc., and more particularly, an U-shaped shock absorbing device fixed to an U-shaped groove disposed on the back side of a heel portion of a midsole of a footwear, an U-shaped shock absorbing member slidably fixed to the U-shaped transparent housing whereby the interior of the shoe can continuously absorbed the shocks to the backside of the foot during walking so that the device provides a cushion function and further a fashion effect.
2. Description of the Prior Art
Various types of insoles for shoes, which have a ventilating and shock absorbing system are well known in the art. Such prior art insoles are shown in the following publications. U.S. Pat. No. 4,499,672 discloses a midsole providing ventilation and shock absorption. The midsole is joined to the outsole by means of projections.
Korean Utility Patent No. 90-2,356 discloses a footwear sole providing ventilation and shock absorption and having a ventilation cap having a fixable connection joint cap. The heel side part of the complementary sole has a cork layer on its surface formed as a circular curve part and projections for a cushion are prepared on the reverse side thereof while on the front, a round projected part is formed as well as cushioning projections with ventilation punched holes. The front part of the midsole has a space part with a round projected part prepared at the inner side of the outskirts.
Korean Utility Patent Publication No. 90-2,537 discloses a footwear sole providing ventilation and shock absorption which has an airing cap fitted to its receptacle. The front part of a soft cushion midsole has punched holes while the reverse side of it has shock absorbing projections. The back part of the reverse side of the cushioned midsole has circular projections while the back part of the outsole has an air inhalation and exhalation opening. The projected part on the front of the heel was prepared for fitting to the airing cap which has ventilation holes and receptacles.
Korean Utility Patent Publication No. 90-2,538 discloses a footwear sole providing ventilation and shock absorption and which has a heel cushioned pad on the surface of the outsole. A soft cushioned pad with a surface of a cork layer is fitted to the inside of the cut part which was prepared at the front part of a hard Texon board midsole. The surface of the cushioned pad was attached to the texon board midsole by a textile net. The reverse side of the cushioned pad has cushioned projections through which ventilation holes extend. The reverse side of the heel cushioned pad has a curve part on its surface containing an air ventilation chamber and an air supply passage. The inner part of the air inhalation chamber has shock absorbing projections.
The above-described technology allows good ventilation within footwear as the airing cap has ventilation holes but cannot effectively prevent water from getting into the footwear in bad weather.
However, the shock absorbing material at the heel is not fitted in the inside of the heel of the sole, and the effective shock absorption at the heel of the shoe cannot be expected. Further, the fact that the cushioned shock absorbing material for the heel is not fitted at a Texon board prevents good shock absorbing effect to the backside of the foot and will not remove the negative factors for the shock absorption when the sole of footwear has a heel, such as shoes, military shoes and mountain climbing shoes, due to the twisted hard iron fitted at the Texon board.
In order to avoid such problems, one approach is a footwear sole having a waterproof and ventilation part secured in the midsole or the outsole, and a horseshoe-shaped shock absorbing heel member secured in the heel portion of the sole part in which the waterproof and ventilation part is secured. The waterproof and ventilation part includes a buoyancy plate that blocks penetration of water into the sole during bad weather. The shock absorbing heel member has opposite flanges with an empty space therebetween that insure very good shock absorbing properties of the shock absorbing heel member. However, the horseshoe-shaped shock absorbing heel member can be twisted or moved, and dust gathers thereon during walking.